Radiological status of Rongelap Island in 1999

A radiological survey and whole body counting of ¹³⁷Cs were carried out in Rongelap Island (main island) of Rongelap Atoll in July 1999. The maximum values of ¹³⁷Cs contamination and of g-ray dose rate were 39 kBq/m² and 0.033 mSv/h, respectively. The maximum a and b gross counting rates on the surface of ground were 1 cpm and 182 cpm in active area of 72 cm², respectively. Activity of ^239,240Pu for soil was 80 Bq/kg in the top 5 cm and aerial deposition was 3.4 kBq/m² in Rongelap Island in 1999. The body burden of ¹³⁷Cs was observed to be 27±11 Bq/kg for 6 workers. Assessment of external and internal annual doses (0.1 and 0.07 mSv/y) indicates that as of 1999 there is no large risk to the inhabitants of Rongelap Island from a radiological point of view. The radiological status of Rongelap Island, which was severely contaminated by the radiological fallouts of nuclear testings carried out in 1954, has improved year by year as shown by the decrease of ¹³⁷Cs. The effective halftime of ¹³⁷Cs, which is estimated to be 6.6 y is much shorter than the physical half-life of ¹³⁷Cs. Radioactive contamination in Kaballe Island, (a part of the northern islands used for farming) which is located 25 km northeast of Rongelap Island, was still high in 1999. One site nearby a beach was highly contaminated with ¹³⁷Cs, where the maximum activity of ¹³⁷Cs was 3.4 MBq/m², a-ray of 2 cpm, b-ray of 1205 cpm and g-ray of 0.73 mSv/h. Activity of ^239,240Pu in soil (n = 1) was 294 Bq/kg (top 5 cm) and 16 kBq/m².     

Electrochemical aptamer sensor for highly sensitive detection of mercury ion with Au/Pt@carbon nanofiber‐modified electrode

In this paper, an electrochemical aptamer sensor was proposed for the highly sensitive detection of mercury ion (Hg²⁺). Carbon nanofiber (CNF) was prepared by electrospinning and high‐temperature carbonization, which was used for the loading of platinum nanoparticles (PtNPs) by the hydrothermal method. The Pt@CNF nanocomposite was modified on the surface of carbon ionic liquid electrode (CILE) to obtain Pt@CNF/CILE, which was further decorated by gold nanoparticles (AuNPs) through electrodeposition to get Au/Pt@CNF/CILE. Self‐assembling of the thiol‐based aptamer was further realized by the formation of Au‐S bond to get an electrochemical aptamer sensor (Aptamer/Au/Pt@CNF/CILE). Due to the specific binding of aptamer probe to Hg²⁺ with the formation of T‐Hg²⁺‐T structure, a highly sensitive quantitative detection of Hg²⁺ could be achieved by recording the changes of current signal after reacting with Hg²⁺ within the concentration range from 1.0 × 10^?15 mol/L to 1.0 × 10^?6 mol/L and the detection limit of 3.33 × 10^?16 mol/L (3σ). Real water samples were successfully analyzed by this method.     

The effect of pre-evaporation on ion distributions in inductively coupled plasma mass spectrometry

The connecting tube (2 or 5-mm i. d., 11-cm long) between the spray chamber and the torch was heated (to 400 °C) to investigate the effect of pre-evaporation on the distribution of ions in inductively coupled plasma mass spectrometry (ICP-MS). Axial and radial profiles of analyte ions (Al⁺, V⁺, Cr⁺, Ni⁺, Zn⁺, Mn⁺, Zn⁺, As⁺, Se⁺, Mo⁺, Cd⁺, Sb⁺, La⁺, Pb⁺) in 1% HNO₃ as well as some polyatomic ions (LaO⁺, ArO⁺, ArN⁺, CO₂⁺) were simultaneously obtained on a time-of-flight ICP-MS instrument. Upon heating the connecting tube, the optimal axial position of all elements shifted closer to the load coil. Without the heated tube, 3.5 mm was the compromise axial position for multielemental analysis, which was optimal for 6 analytes. With the heated tube, this position became 1.5 mm, which was then optimal for 9 of the 14 analytes. Furthermore, the radial profiles, which were wide with a plateau in their middle without heating, became significantly narrower and Gaussian-like with a heated tube. This narrowing, which was most important for the 5-mm tube, slightly (by a factor of two at the most) yet significantly (at the 95% confidence level) improved the sensitivity of all elements but Mn upon optimisation of the axial position for compromise multi-element analysis. Furthermore, a concurrent decrease in the standard deviation of the blank was significant at the 95% confidence level for 9 of the 14 analytes. For most of the analytes, this translated into a two-fold to up to an order of magnitude improvement in detection limit, which is commensurate with a reduction of noise resulting from the smaller droplets entering the plasma after traversing the pre-evaporation tube.     

Application of PXAMS technique for 36Cl analysis in soil collected at Semipalatinsk Nuclear Test Site

³⁶Cl in soil samples from the Semipalatinsk Nuclear Test Site (former USSR) was measured at Kyushu University Tandem Laboratory (KUTL) by accelerator mass spectrometry (AMS) coupled with projectile X-ray detection (PXD) technique. The separation of competing ³⁶S and ³⁶Cl atomic isobars, was satisfactory by PXD technique. Measured ³⁶Cl/Cl atom ratio was (5.0±0.6)^.10^–10 and an average activity of ³⁶Cl was calculated as (2.0±0.2) mBq/g, which is in a good agreement with that obtained by liquid scintillation counting (LSC) method previously. Currently developed AMS system at the Kyushu University can be applied for routine ³⁶Cl analysis at ³⁶Cl/Cl = 10^–11 atom ratio level.     

Preparation and analysis of14C-lignin grass lignocellulose and DHP

(¹⁴C-lignin) grass lignocellulose was prepared from wheat seedlings injected with (¹⁴C-uniform) phenylalanine. Seedlings were injected 2 wk after germination and grown for 3–4 wk in a diurnal light cycle before harvesting. The plant material was ground in liquid N₂, extracted with hot water, benzene-ethanol, and ethanol, and treated with protease. Treatment of the lignocellulose with acid, alkali, and cellulase solubilized¹⁴C, which was analyzed by HPLC and TLC. Reverse-phase HPLC demonstrated that¹⁴C-ferulic and coumaric acid were bound primarily to carbohydrate and lignin, respectively. Gel permeation chromatography by HPLC of¹⁴C solubilized by treatment with 1M NaOH confirmed that the majority of the¹⁴C was incorporated into high molecular weight material. No¹⁴C was detected in either hexoses or pentoses obtained from the lignocellulose and only a minor amount was present as¹⁴C-phenylalanine. These studies show that (¹⁴C-lignin) grass lignocelluloses must be carefully characterized before being used as defined substrates for biodegradation studies. Coniferyl alcohol was synthesized by a route derived from those of Nakamura et al. (1974) and Nakamura and Higuchi (1976). DHP was then prepared by a modification of the method of Brunow and Wallin (1981) in which solutions of coniferyl alcohol and hydrogen peroxide were added alternately by a computer controlled HPLC system so that the coniferyl alcohol concentration was maintained below 1 mM throughout the synthesis. The DHP obtained was characterized by HPLC gel permeation chromatography and by NMR. The results of these analyses will be discussed.     

Importance of Outer‐Sphere and Aggregation Phenomena in the Relaxation Properties of Phosphonated Gadolinium Complexes with Potential Applications as MRI Contrast Agents

A series composed of a tetra‐, a tris‐ and a bisphosphonated ligand based on a pyridine scaffold ( L⁴ , L³ and L² , respectively) was studied within the frame of lanthanide (Ln) coordination. The stability constants of the complexes formed with lanthanide cations (Ln=La, Nd, Eu, Gd, Tb, Er and Lu) were determined by potentiometry in aqueous solutions (25.0 °C, 0.1 M NaClO₄), showing that the tetraphosphonated complexes are among the most stable Ln^III complexes reported in the literature. The complexation of L⁴ was further studied by different titration experiments using mass spectrometry and various spectroscopic techniques including UV/Vis absorption, and steady state and time‐resolved luminescence (Ln=Eu and Tb). Titration experiments confirmed the formation of highly stable [Ln L⁴ ] complexes. ³¹P NMR experiments of the Lu L⁴ complex revealed an intramolecular interconversion process which was studied at different temperatures and was rationalized by DFT modelling. The relaxivity properties of the Gd^III complexes were studied by recording their ¹H NMRD profiles at various temperatures, by temperature dependent ¹⁷O NMR experiments (Gd L⁴ ) and by pH dependent relaxivity measurements at 0.47 T (Gd L³ and Gd L² ). In addition to the high relaxivity values observed for all complexes, the results showed an important second‐sphere contribution to relaxivity and pH dependent variations associated with the formation of aggregates for Gd L² and Gd L³ . Finally, intravenous injection of Gd L⁴ to a mouse was followed by dynamic MRI imaging at 1.5 T, which showed that the complex can be immediately found in the blood stream and rapidly eliminated through the liver and in large part through the kidneys.     

Synthesis and cell uptake of a novel dualmodality (188)Re-HGRGD (D) F-CdTe QDs probe

A novel dualmodality probe was prepared by linking ¹⁸⁸Re-HGRGD (D) F with CdTe QDs, which was monitored using radio-thin layer chromatography (TLC) and -high performance liquid chromatography (HPLC). The ¹⁸⁸Re-HGRGD (D) F-CdTe QDs probe possesses a radiochemistry yield of 92.1% and strong photoluminescence (PL) stability. However, the radiochemical purity of ¹⁸⁸Re-HGRGD (D) F-QDs would reduce to 74.8%, which should be further improved, after incubation with newborn calf serum (NCF) for 24 h. Human glioblastoma U87MG cells, known to express a high-affinity to RGD, were used to assess the in vitro cell binding of probe. The results showed that the radio-signal was in accord with the change of PL intensity, which meant the successful integration of ¹⁸⁸Re and QDs.     

Reexamination of the theory of exaltation of the migration current by preceding electrode reactions

The effect of the preceding current of Hg(CN)₂, CdSO₄, ZnSO₄, and HCl on the K⁺ wave, of Hg(CN)₂ and CuSO₄ on the Cd²⁺ wave, of CdSO₄ on the Zn²⁺ wave, and of Hg(CN)₂ and CdSO₄ on the IO^?₃ wave was investigated. No exaltation of the Cd²⁺ wave was observed and only small variations of the Zn²⁺ and IO^?₃ waves. The increase of the K⁺ waves was roughly in accord with the prediction of the theory of the so-called exaltation of migration currents by preceding electrochemical reactions. However, the exaltation can be explained by concomitant reactions of K-amalgam with water and electrochemical reduction of hydrogen, which are accelerated by other ions (and also by the ions involved in the preceding reactions) and which, consequently, invalidate the equation of the exaltation of migration currents.     

Monitoring Humic Acid Photodegradation by CUPRAC Colorimetric and HPLC Determination of Dihydroxybenzoate Isomers Produced From a Salicylate Probe

Abstract

Novel analytical methods were designed for monitoring humic acid photodegradation in environmental waters. Modified CUPric Reducing Antioxidant Capacity (CUPRAC) spectrophotometric and chromatographic methods were used for the determination of dihydroxybenzoate isomers (DHBAs) produced from a salicylate probe, which was hydroxylated by hydroxyl radicals (^?OH) produced from the photodegradation of humic acid under ultraviolet A-radiation. The combined use of CUPRAC colorimetry and HPLC was shown to effectively monitor humic acid photodegradation and ^?OH generation for the first time. The formation of 2,5-dihydroxybenzoate and 2,3-dihydroxybenzoate, as major and minor products, respectively, from the hydroxylation of a salicylate probe was demonstrated by HPLC and confirmed by a modified CUPRAC method to indicate ^?OH formation from humic acid, which acted as both a generator and absorber of hydroxyl radicals. Salicylate hydroxylation showed an increase between 30 and 50?min of illumination, and was affected by the initial concentration of humic acid up to 0.01% but not by solution pH around the neutral values. Traces of Fe(III) and Mn(II) present in natural waters decreased the ^?OH production, but EDTA partly restored the probe hydroxylation by chelating these metal cations. Since humic acid-mediated ^?OH generation may aid in natural disinfection processes, this work may extend our comprehension of concentration- and time-dependent generation of ^?OH in environmental waters and of the possible effects of other antioxidants.     

Studies on the Reactivity of [Ge9]4− towards [Fe(cot)(CO)3]: Synthesis and Characterization of [Ge8Fe(CO)3]3− and of the Anionic Organometallic Species [Fe(cot)(CO)3]−

Reaction of cyclooctatetraene (COT) iron(II) tricarbonyl, [Fe(cot)(CO)₃], with one equivalent of K₄Ge₉ in ethylenediamine (en) yielded the cluster anion [Ge₈Fe(CO)₃]^3? which was crystallographically‐characterized as a [K(2,2,2‐crypt)]⁺ salt in [K(2,2,2‐crypt)]₃[Ge₈Fe(CO)₃]. The chemically‐reduced organometallic species [Fe(η³‐C₈H₈)(CO)₃]^? was also isolated as a side‐product from this reaction as [K(2,2,2‐crypt)][Fe(η³‐C₈H₈)(CO)₃]. Both species were further characterized by EPR and IR spectroscopy and electrospray mass spectrometry. The [Ge₈Fe(CO)₃]^3? cluster anion represents an unprecedented functionalized germanium Zintl anion in which the nine‐atom precursor cluster has lost a vertex, which has been replaced by a transition‐metal moiety.     

Mg-induced vesicles of tetradecyldimethylamine oxide and magnesium dodecyl sulfate

A Mg²⁺-induced vesicle phase was prepared from a mixture of tetradecyldimethylamine oxide (C₁₄DMAO) and magnesium dodecyl sulfate [Mg(DS)₂] in aqueous solution. Study of the phase behavior shows that at the appropriate mixing ratios, Mg²⁺–ligand coordination between C₁₄DMAO and Mg(DS)₂ results in the formation of molecular bilayers, in which Mg²⁺ can firmly bind to the head groups of the two surfactants. The area of the head group can be reduced because of the complexation. In this case, no counterions exist in aqueous solution because of the fixation of Mg²⁺ ions to the bilayer membranes. Therefore, the charges of the bilayer membranes are not shielded by salts. The birefringent solutions of Mg(DS)₂ and C₁₄DMAO mixtures consist of vesicles which were determined by transmission electron microscopy (TEM) images and rheological measurements. Magnesium oxide (MgO) nanoplates were obtained via the decomposition of Mg(OH)₂ which were synthesized in Mg²⁺-induced vesicle phase which was used as the microreactor under the existence of ammonia hydroxide. The morphologies and structures of the obtained MgO nanoplates have been characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results indicate that the crystal growth is along the (1 1 1) direction which can be affected by the presence of a vesicle phase having a fixation of Mg²⁺ ions to the bilayer membranes.     

Specific stimuli‐responsive antipolyelectrolyte swelling of amphiphilic gel based on methacryloxyethyl dimethyloctane ammonium bromide

An amphiphilic electrolyte, methacryloxyethyl dimethyloctane ammonium bromide (MODAB), was synthesized by quaternization of dimethylaminoethyl methacrylate (DMAEMA) with 1‐bromooctane. Then amphiphilic PMODAB gel was synthesized by radiation cross‐linking with ethyleneglycol dimethacrylate as cross‐linker. PMODAB gels possess distinguished different swelling behaviors with those of DMAEMA hydrogels: (1) Antipolyelectrolyte phenomenon was observed in NaCl solution, that is, a remarkable increment of equilibrium degree of swelling (EDS) in the low NaCl concentration region (10^?4 to 10^?3 mol L^?1), followed by a significant decrease (10^?3 to 0.2 mol L^?1), and a collapsed state (>0.2 mol L^?1); (2) Compared with PDMAEMA, PMODAB was a temperature‐sensitive polymer which showed an upper critical solution temperature (UCST) behavior. The EDS of PMODAB gel dramatically increased at the UCST; (3) In the 0.2 mol L^?1 NaCl solutions, PMODAB gel swelled more significantly in a basic condition (pH > 10) than that in an acidic condition. The special volume phase transition behavior of PMODAB gel is ascribed to the hydrophobic interaction between octyl groups and the formation of ion‐cluster between tetra‐alkyl ammonium cation and Br^?, which lead to the aggregation of gel structure and could be affected by the composition and temperature of the surrounding solution. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 473–480, 2008     

Solvent Extraction of Rhenium(VII) for Preparation of No-Carrier-Added 186Re Saline Solution with High Specific Volume Activity

By using ¹⁸⁸Re as a radiotracer, the extraction behavior of Re(VII) by a tertiary amine extractant N-235 from HCl and the back-extraction behavior of Re(VII) by HNO₃ and ammonia were studied. A chemical separation procedure, which combined the acid alumina column and solvent extraction was established. The procedure was rapid and efficient for the separation of ¹⁸⁶Re from ¹⁸⁶W irradiated by 16 MeV deuterons. No-carrier-added ¹⁸⁶ReO₄ ^– saline solution with high specific volume activity was obtained. The overall recovery yield of ¹⁸⁶Re was about 85%.     

Characterisation of thin solid Xe targets

A series of frozen xenon targets of thicknesses ranging between 1 and 15 mg/cm² were characterised by elastic backscattering technique using a 3 MeV proton beam. Xenon was kept solid on a gold substrate having a thickness of 1 g/cm² which was mounted on a cold copper finger. The temperature of targets during the experiment was maintained at 55 K by a compact solid nitrogen sublimation system under pressure of 10^?5 mbar. Targets were used in series of experiments for populating samarium and gadolinium isotopes in the ¹³⁶Xe (¹⁸O, Xn) and ¹³⁶Xe (²²Ne, Xn) nuclear reactions.     

Preparation of manganese-53

The nuclide⁵³Mn was produced by the following three nuclear reactions,⁵²Cr(d, n)⁵³Mn,⁵¹V(³He n)⁵³Mn and⁵⁰Cr(α, n), (α, p)⁵³Mn. Enriched⁵²Cr and⁵⁰Cr metal targets were prepared on copper plate holder by electrodeposition. The commercially available natural vanadium foil was used for the⁵¹V(³He, n)⁵³Mn reaction. Each target was bombarded in a cyclotron. Manganese was extracted and purified without using carrier from the bombarded targets by anion and cation exchanges and solvent extraction. The isotopic ratio⁵³Mn/⁵⁵Mn was measured by mass spectrometry and the amount of⁵⁵Mn was determined by neutron activation analysis. The activity of⁵³Mn obtained was 7 dpm by 750 millicoulombs in³He bombardment (E³He=20 MeV). The activity due to by-product⁵⁴Mn was about several thousands times higher than that of⁵³Mn in³He and deuteron bombardments, which were produced through⁵¹V(³He, γ)⁵⁴Mn and⁵³Cr(d, n)⁵⁴Mn. In alpha bombardment (E_α=15 MeV), the activity of⁵³Mn produced was 8 dpm by 95 millicoulombs. The activity ratio, dpm⁵⁴Mn/dpm⁵³Mn, was about 3, and this ratio was the best one among the results so far obtained.     

Photoreaction of Ketoprofen with Tryptophan and Tyrosine in Phosphate Buffer Solution

Reaction of excited ketoprofen (KP) with tryptophan (Trp) and tyrosine (Tyr) in a phosphate buffer solution was studied by the transient absorption spectroscopy. Both amino acids, which would interact with KP in bovine serum albumin [Monti, S. [2009] Phys. Chem. Chem. Phys., 11, 9104–9113], accelerated the proton transfer reaction to yield 3‐ethylbenzophenone ketyl biradical (EBPH) from KP carbanion, which was produced by photoexcitation of KP^? through decarboxylation. By means of the actinometry method with benzophenone, the reaction quantum yield was successfully estimated to be fairly large, and Trp, Tyr, DOPA and 4‐methylphenol were found to be a good proton donor for the carbanion. The formation rate constants of EBPH by the amino acids (k_r) were also determined to be (2.7 ± 0.1) × 10⁹ M^?1s^?1 for Trp and (7.8 ± 0.4) × 10⁸ M^?1s^?1 for Tyr, which were larger than those by basic amino acids and dipeptides reported. The reason for the highly efficient proton transfer reaction with Trp and Tyr would be explained by difference of the activation energy for the reaction. These results suggest that the proton transfer should be a key process for an initial photoreaction of KP with a protein, causing photosensitization in vivo.     

Initiation of cationic polymerization of n-butyl vinyl ether by stable cation radicals of substituted phenothiazines

3,7-Diethyl- 10-phenylphenothiazine (DEPPT), a phenothiazine derivative whose 3,7- and 10-positions are blocked, was synthesized. Potentiostatic electrolysis of DEPPT in acetonitrile (ACN) in the presence of 0.1M of LiClO₄ at 0.7 V (vs. Ag/Ag/Cl) yielded the stable cation radical of DEPPT (DEPPT^+·) which was characterized by cyclic voltammetry, UV-visible spectroscopy, and ESR spectrometry. Stable cation radicals of 10-phenylphenothiazine and 3,7-diethyl-10-methylphenothiazine were also prepared. The cationic polymerization of n-butyl vinyl ether was initiated by these cation radicals, including DEPPT^·+. The electron transfer mechanism for the initiation step, which we proposed previously, was supported by the fact that DEPPT^·+ was capable of initiating the polymerization; dimerization of DEPPT^·+ by releasing protons is precluded because 3,7- and 10-positions are all blocked. © 1994 John Wiley & Sons, Inc.     

A Bifunctional Luminescent Metal–Organic Framework for the Sensing of Paraquat and Fe3+ Ions in Water

The hydrothermal reaction of Zn²⁺ ions with a mixture of two ligands, Hcptpy and H₃btc (Hcptpy=4‐(4‐carboxyphenyl)‐2,2′:4′,4′′‐terpyridine; H₃btc=1,3,5‐benzenetricarboxylic acid), led to the formation of a 3D metal–organic framework (MOF) with 1D channels, [Zn₂(cptpy)(btc)(H₂O)]_n ( 1 ), which was structurally characterized by using single‐crystal X‐ray diffraction (SXRD). In MOF 1 , two independent Zn²⁺ ions were interconnected by btc^3? ligands to form a 1D chain, whilst adjacent Zn²⁺ ions were alternately bridged by cptpy^? ligands to generate a 2D sheet, which was further linked by 1D chains to form a 3D framework with a new (3,3,4,4)‐connected topology. Furthermore, compound 1 also exhibited excellent stability towards air and water and, more importantly, luminescence experiments indicated that it could serve as a probe for the sensitive detection of paraquat (PAQ) and Fe³⁺ ions in aqueous solution.     

The Electronic Ground State of [Fe(CO)3(NO)]−: A Spectroscopic and Theoretical Study

During the past 10 years iron‐catalyzed reactions have become established in the field of organic synthesis. For example, the complex anion [Fe(CO)₃(NO)]^?, which was originally described by Hogsed and Hieber, shows catalytic activity in various organic reactions. This anion is commonly regarded as being isoelectronic with [Fe(CO)₄]^2?, which, however, shows poor catalytic activity. The spectroscopic and quantum chemical investigations presented herein reveal that the complex ferrate [Fe(CO)₃(NO)]^? cannot be regarded as a Fe^?II species, but rather is predominantly a Fe⁰ species, in which the metal is covalently bonded to NO^? by two π‐bonds. A metal–N σ‐bond is not observed.     

HCNO分子裂解机理的理论研究

实验提示应用248 nm UV波长对HCNO分子进行直接光解, 该分子可能发生裂解, 得到某些产物. 为了揭示HCNO分子的裂解机理, 选择HCNO分子的一组相对能级作为理论研究的起始点, 即¹A' (0.00 kJ/mol), ³A' (255.01 kJ/mol), ³A" (282.37 kJ/mol)和¹A" (341.59 kJ/mol), 进而找到了合理的反应路径, 阐明了相应的裂解机理, 得到的主要产物为H＋NCO, HCN＋O和NH＋CO, 与实验提示的结果相符合.